I have a fan (hot, neutral, ground) that requires 120V and uses 1amp max. I'd like to be able to control this with a thermostat so that the fan turns on when the temperature is above a certain set point. The thermostat I'm looking at, Nest, requires 3 wires ... 24VAC, a neutral, and a switch wire. When the thermostat activates the circuit, it connects the neutral to the switch wire.

How can I control the 120V circuit with this low-voltage thermostat? And is there a way to pull 24VAC power at the same time to run the thermostat?

I was thinking I'd need a 120V to 24V transformer, but I'm not sure how the switch circuit would look.

Reader keep in mind that in this description that "neutral" of the 24VAC transformer/relay coil/thermostat is a separate circuit from "neutral" of the relay contact/AC source/fan. These two "neutrals" are not meant to be tied together.
–
Michael KarasJul 13 '14 at 0:21